Multicolor sheet-fed printing press

ABSTRACT

Multicolor sheet-fed printing press having a pair of two-color printing units, each of which includes horizontally offset upper and lower printing couples. The two-color units are likeconstructed and like-facing, and each is provided with an operator platform generally below and alongside the lower printing couple, whereby an operator on the platform can service both printing couples of a two-color unit from a single location. The two-color unit which is first to print sheets passing through the press is higher than the second unit, and a series of transfer cylinders are provided to carry sheets between the twocolor units.

Unite States Patent [191 Southam et al.

[ Nov. 11, 1975 MULTXCOLOR SHEET-FED PRINTING PRESS [21] Appl. No.:130,167

[52] U.S. Cl 101/183; 101/136 Harris 101/142 2,554,904 5/1951 Harrold101/183 X 2,577,099 12/1951 Albrecht 101/183 2,757,610 8/1956Gegenheimer et a1... 101/183 2,898,851 8/1959 Peyrebrune 101/1363,527,164 9/1970 Bulk i 101/137 3,537,391 11/1970 Mowry... 101/230 X3,570,398 3/1971 Mowry 101/183 Primary Examiner-=1. Reed Fisher [57]ABSTRACT Multicolor sheet-fed printing press having a pair of two-colorprinting units, each of which includes horizontally offset upper andlower printing couples. The two-color units are like-constructed andlike-facing, and each is provided with an operator platform generallybelow and alongside the lower printing couple, whereby an operator onthe platform can service both printing couples of a two-color unit froma single location The two-color unit which is first to print sheetspassing through the press is higher than the second unit, and a seriesof transfer cylinders are provided to carry sheets between the two-colorunits.

4 Claims, 1 Drawing Figure U.S. Patent Nov. 11, 1975 MULTICOLORSHEET-FED PRINTING PRESS Shortly afteer the second World War, certainprinting press manufacturers introduced medium-sized twocolor sheetfedlithographic presses constructed with both printing couples mounted in acommon frame. The printing couples were offset both vertically andhorizontally to provide upper and lower couples. Alongside the lowercouple was a platform on which an operator could stand to enableservicing either or both printing couples from one location. The successof these presses was and continues to be outstanding. An example of onetype of two-color press referred to is shown in U.S. Pat. No. 2,542,867.This was followed in the late 1950s and early 1960s with four-colorpresses which essentially consisted of a pair of these two-colorprinting units connected together by what is commonly called a chaintransfer system. Four-color presses of this type are illustrated in U.S.Pat. Nos. 2,705,918 and 3,527,164, and are commonly referred to astandems in the printing trade.

Although chain transfer systems have been used satisfactorily for manyyears, they are not without limitations. For example, chain transfersystems are difficult to manufacture, assemble and maintain in a stateof high accuracy for highest quality lithography. To have each of aplurality of chain transfer gripper sets repeatedly register identicallywith all other sets in receiving a sheet from one two-color printingunit and transferring that sheetto a subsequent printing unit is anaccomplishment not easily obtained. Unless all the complex mechanismsare manufactured, assembled and continually maintained almost perfectlyto tolerances of 0.001 inch or less, it is possible to get as manydifferent color prints in each successive series of sheets as there aregripper sets in the chain transfer system. Misregister between thetwo-color units causes a fault commonly known as doubling Doublingoccurs when some of the ink received by a given sheet from the first twoprinting couples is offset out of register onto the blankets of thethird and fourth printing couples, and, by this ink being out ofregister with the next following sheet, the third and fourth couplesprint it back onto that next following sheet in an incorrect position.This misregister in multicolor half-tone printing has the effect ofcolor change and the importance of accurate register to avoid such aresult is too well known in highgrade lithography to require furthercomment.

it has been known that improved printing register is possible throughuse of a cylinder transfer mechanism between printing couples. However,the arrangement of the printing couples in the tandem presses shown inU.S. Pat. Nos. 3,527,164 and 2,705,918 is such that the number ofcylinders required for sheet transfer is too great and too costly tojustify conversion from the chain transfer system.

This invention relates to an improvement over conventional four-colorchain transfer type presses wherein the first of the two-color printingunits is ele- .vated above the second two-color unit, whereby acommercially feasible press capable of producing high qualitylithography is provided with a minimumnumber of sheet transfer cylindersbetween the two-color units. In the preferred embodiment, an odd numberof transfer cylinders is provided between the two-color units, all orcertain ones of which are double the diameter of the cylinders of theprinting couples.

The sole FIGURE illustrates a simplified side elevational view of aprinting press embodying the invention.

In the preferred form of printing press illustrated, sheets are fed fromright to left from a pile feeder 10, supporting and automaticallyraising a pile of sheets 11, from the top of which individual sheets arefed one at a time. A conventional sheet separating mechanism (not shown)is supported between side frames of the pile feeder above the pile 11.As sheets are separated, they are forwarded in underlapping streamfashion down an inclined feed table 12, at the lower end of which is astock register unit 13. Each sheet is front and side registered in turnat the stock register unit, and is then fed to grippers on an impressioncylinder 14 of a first printing couple 15. Generally, the printingcouple 15 includes, in addition to impression cylinder 14, a

blanket cylinder 16, a plate cylinder 17 and, in the exampleillustrated, a combined inker and lithographic dampener 18 positionedabove the plate cylinder 17. The printing'couple itself may be of anytype, and the one shown herein is a commercial version presently on themarket. Many details of the other printing couples of the press havebeen omitted, and it is to be understood that they are preferably of thesame construction as couple 15.

As shown, the impression cylinder 14 rotates counterclockwise andprovides a supporting surface for a sheet carried by gripper fingers 19.The fingers 19 transport the sheet in register through a printing nipformed by the cylinders 14 and 16.

Each sheet is thereafter transferred to gripper fingers on a transfercylinder 50, which is shown as being twice the diameter of each of thecylinders of the first printing couple 15. The transfer cylindergrippers carry the sheet clockwise around its lower surface and transferit to a second impression cyiinder 20 of a second printing couple 21.The sheet is subsequently passed around successive sheet-carryingtransfer and impression cylinders 2227, all of which are shown as beingdouble diameter transfer cylinders with the exception of impressioncylinder 25 of the third printing couple 28 and impression cylinder 27of the fourth printing couple 29.

After receiving the fourth color, sheets are transferred to grippers 30of a delivery system including a delivery cylinder 31 and a continuouschain 32. The grippers 30 deposit sheets on the top of a pile 33, whichis automatically lowered in the usual manner as sheets build up thereon.The chain 32 has a plurality of sets of grippers 30, only certain onesof which are shown, it being understood that they are equally spacedthroughout the length of the chain. The main portion of the deliverysystem pile is supported in a pile delivery 34.

All of the cylinders described extend parallel to each other onhorizontal axes between spaced side frames which journal the cylinders.The frames of the pile feeder 10, stock register 13 and the piledelivery 34 are similarly provided in spaced pairs. All of the framesare shown in dotted lines for ease of description.

' It will be noted that the printing couples l5 and 21 are mountedbetween side frames 35 while printing couples 28 and 29 are supportedbetween side frames 36. The side frames 35 and 36 may be made unitary orof subsections and, for all practical purposes, the frames areessentially the same. A principal difference is in the mounting oftransfer cylinder 22 in frame 35 as compared to the mounting of deliverycylinder 31 in the side frame 36. The side frames 35 and 36 areinterconnected on each side of the press by subframes 37 which supporttransfer cylinders 23 and 24.

At the left and lower side of the printing couples 21 and 29 are locatedoperator platforms 38 and 39, respectively. From platforms 38 and 39, anoperator standing, stooping or kneeling on those platforms can servicemost, if not all, of the two printing couples and their inkers,depending on the construction of the twocolor unit. Installation ofprinting plates and blankets on their respective plate and blanketcylinders, servicing of the inkers, or washing any of the units can takeplace from the platforms 38 and 39 on the two printing couplesimmediately to the right of the platforms as shown in the drawing. As anexample of this, one can refer to U.S. Pat. No. 2,542,867 issued to C.W. Harrold on Feb. 29, 1951. The press herein illustrated is essentiallya pair of two-color printing units of the type illustrated in thatpatent.

Although two-color presses of the general type described above have beenavailable on the world market for over years, it was not until the late1950s that such presses were connected together to make a fourcolorprinting press from a pair of these two-color printing units. Examplesof such four-color presses can be seen in U.S. Pat. Nos. 3,527,164 and2,705,918. The only known solution to the problem of making a fourcolorpress out of a pair of these two-color units has been to utilize a chaintransfer system approach as the method of transporting sheets betweenunits. While a large number of such presses have been sold and are inuse in the printing industry today, they sometimes have problemsobtaining highly accurate printing register in multicolor work.Obviously, when using a chain transfer sytem, each of the plurality ofgripper sets must be identical with all of the others, and must registerperfectly to a first cylinder at one end of the chain transfer when theyreceive a sheet from one impression cylinder, and again registerperfectly at the other end of the chain transfer when they give up thesheet to a subsequent impression cylinder. The manufacturing andassembling tolerance requirements in this type of mechanism are believedby many to be much greater and must be held more closely than inconventional cylinder transfer systems. Print repeatability is much moredifficult to obtain when gripper sets are allowed to travel looselysupported by chains, then must be registered and locked to a cylindermechanism before receipt of a sheet, again allowed to be loose on theflexible chain, and then finally re-registered and locked to anothercylinder at the opposite end of the chain transfer. These presses arequite satisfactory for a large percentage of multicolor printing, butfor top quality lithography, they must be manufactured with extremeaccuracy and carefully maintained in that condition. Nevertheless, untilthis invention, the chain transfer system has been the only knowncommercial solution to the problem of providing a four-color tandempress by connecting a pair of two-color printing units of the typediscussed previously. Certainly, cylinder transfer was known to bepreferred, but to connect such a pair of two-color printing units bytransfer cylinders in the normal way would require an excessive numberof transfer cylinders between the pairs of units. Various transfercylinder arrangements have been considered over the years, all resultingin designs with excessive numbers of cylinders, thus making themuneconomical to produce.

This invention makes it possible to obtain the advantages of cylindertransfer in a tandem four color press while avoiding the problems ofcost and complexity which have resulted from attempts to substitute acylinder transfer system in the same location as a chain transfersystem. More specifically, this invention contemplates verticallyoffsetting side frame of the first two-color unit higher than frame 36of the second twocolor unit. This is accomplished by placing a subframebeneath each of the side frames 35, so as to raise the entire two-colorprinting unit which contains printing couples 15 and 21. In thisfashion, the pairs of twocolor units are maintained substantiallyidentical, and remain compatible with the standard two-color presses ofU.S. Pat. No. 2,542,867. It is preferred also to raise the pile feeder10 by mounting beneath the side frames thereof, a pair of subframes 41.This provides a capability of handling higher piles of sheets 11 in thepile feeder 10, if desired. A standard-height feeder may be used, and insuch case, an additional in-feed cylinder or cylinders would be locatedbetween the stock register unit 13 and the first impression cylinder 14.

A very important aspect of the invention is to provide a multicolorsheet-fed printing press which provides maximum accessibility to anoperator for those things which must be done in preparing for printing,actually printing, and cleaning up after a printing job has beencompleted. Since an operator must frequently handcarry things to andfrom the press, such as a printing plate which is preferably carred withboth hands, we provide a two-level platform 42 which is shown in dotdashlines. These platforms 42 are provided on both sides of the press togain operator accessibility to all areas of the press. It will be notedthat the lower level of the platform 42 is made to coincide with theupper surface of the platform 39, so that an operator servicing theprinting couples 28 and 29 can do so by merely making one step up fromthe level of floor 43. To reach platform 38 to service printing couplesl5 and 21, the operator can step up to the second level of the platform42, and then up once again to platform 38. Platforms 38 and 39 extendfully across the press between the platforms 42 on each side thereof.

The press shown in the drawing provides all of the advantages of thechain transfer presses in terms of reduced manpower requirements, (sinceone operator can service two units), has only a slight disadvantage byhaving platform 38 raised three steps above the floor level, but has avery pronounced advantage in terms of accuracy of printing register byelimination of sheet transfer by gripper sets of a chain system. Byraising the frames 35 which support the first two-color printing unit,it is possible to minimize the number of transfer cylinders required tocarry sheets from the impression cylinder 20 of printing couple 21 tothe impression cylinder 25 of printing couple 28. This is accomplishedthrough use of three double-size transfer cylinders 22, 23, and 24, butcan also be achieved through use of single-sized cylinders or acombination of the two. Five cylinders would possibly be commerciallyacceptable. Since the two-color printing units shown already employdouble diameter transfer cylinders and 26, the preferred arrangement ofcylinders is to use similar double diameter transfer cylinders betweenthe impression cylinders 20 and 25. This provides manufacturingadvantages and further reduces the number of actual physical transfersof a given sheet through the press.

Starting at impression cylinder 14' where it passes a sheet to gripperfingers on transfer cylinder 50, it will be seen that there are onlyeight sheet transfers to the final gripper fingers on the impressioncylinder 27 of the fourth printing couple 29. Thus, the use ofdoublesize transfer cylinders 22-24 reduces the number of actual sheettransfers to a minimum, while retaining the general configuration of'thetwo-color printing units which has been so successful in the printingindustry. To provide accessibility to an operator or serviceman of thelower areaof the impression cylinder 27 and delivery cylinder 31, space44.is provided below the subframes 37. A person can lie on a crawlerboard and roll himself into position horizontally below cylinders 23 and24, from which he can reach cylinders 27 and 31. This access is alsonecessary in a four-color press using the common-impression cylinderarrangement for two printing couples as shown in US. Pat. No. 2,705,918,but only for access to its delivery cylinder. Other aspects of theinvention are also believed applicable to such-a common-impression,two-color printing unit.

Although the invention has been described with reference to a specificembodiment, neither the illustrated embodiment nor the terminologyemployed in describing it is intended to be limiting; rather, it isintended to be limited only by the scope of the appended claims.

Having described our invention, we claim:

1. A multicolor sheet-fed printing press comprising first and secondlike-constructed and like-facing twocolor printing units each of whichincludes an upper printing couple having a first impression cylinder, alower printing couple having a second impression cylinder which isoffset downwardly and forwardly approximately 45 from the upper couplein a manner which eliminates the possibility of an operator standingbetween the upper and lower couples of each unit, and a transfercylinder between the first and second impression cylinders of each unitand an operator platform below and along the side of the lower printingcouple remote from the upper couple of each said two-color said numberof transfer cylinders extending generally horizontally below theoperator platform adjacent the lower printing couple of the first unit,the improvement comprising: said first two-color unit being located at ahigher level than said second two-color unit whereby the lower printingcouple of the first unit and the upper printing couple of the secondunit are at approximately the same horizontal level' in order tominimize the horizontal distance said number of transfer cylindersextends I from the lower impression cylinder of the first unit to theupper impression cylinder of the second unit.

2. A printing press according to claim 1 wherein each of said impressioncylinders is of the same diameter and rotates 360 in a single pressrevolution, and wherein each of the transfer cylinders of the two-colorunits and the transfer cylinders between units is twice the diameter ofan impression cylinder and rotates 180 in a single press revolution.

3. A printing press according to claim 2 wherein the transfer cylindersbetween units are three in number.

4. A printing press according to claim 3 wherein the first and second ofthe between-unit transfer cylinders have their axes in approximately thesame horizontal plane, and wherein the third one of said transfercylinders is located upwardly and at an angle of approximately 45 fromthe second one of said transfer cylinders.

1. A multicolor sheet-fed printing press comprising first and secondlike-constructed and like-facing two-color printing units each of whichincludes an upper printing couple having a first impression cylinder, alower printing couple having a second impression cylinder which isoffset downwardly and forwardly approximately 45* from the upper couplein a manner which eliminates the possibility of an operator standingbetween the upper and lower couples of each unit, and a transfercylinder between the first and second impression cylinders of each unitand an operator platform below and along the side of the lower printingcouple remote from the upper couple of each said twocolor unit, each ofsaid impression cylinders and the transfer cylinder of each unit havingat least one set of sheet-carrying gripper fingers thereon, an unevennumber of cooperating, adjacent transfer cylinders each of whichincludes at least one set of sheet-carrying gripper fingers thereon forreceiving sheets from the gripper fingers of said second impressioncylinder of the first unit and transferring them to the gripper fingersof the first impression cylinder of the second unit, said number oftransfer cylinders extending generally horizontally below the operatorplatform adjacent the lower printing couple of the first unit, theimprovement comprising: said first two-color unit being located at ahigher level than said second two-color unit whereby the lower printingcouple of the first unit and the upper printing couple of the secondunit are at approximately the same horizontal level in order to minimizethe horizontal distance said number of transfer cylinders extends fromthe lower impression cylinder of the first unit to the upper impressioncylinder of the second unit.
 2. A printing press according to claim 1wherein each of said impression cylinders is of the same diameter androtates 360* in a single press revolution, and wherein each of thetransfer cylinders of the two-color units and the transfer cylindersbetween units is twice the diameter of an impression cylinder androtates 180* in a single press revolution.
 3. A printing press accordingto claim 2 wherein the transfer cylinders between units are three innumber.
 4. A printing press according to claim 3 wherein the first andsecond of the between-unit transfer cylinders have their axes inapproximately the same horizontal plane, and wherein the third one ofsaid transfer cylinders is located upwardly and at an angle ofapproximately 45* from the second one of said transfer cylinders.